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Did ‘Martian’ methane signal come from Earth?

By Rachel Courtland

CLAIMS that Mars’s atmosphere contains methane, which have fuelled speculations that the planet hosts life, may be premature.

A key piece of evidence for methane on Mars may actually be due to Earth-based methane, warn researchers led by Kevin Zahnle of NASA’s Ames Research Center in Moffett Field, California. “This is not a done deal,” says Zahnle, despite a widespread perception that methane has been found on the Red Planet.

The clearest evidence for methane on Mars came in 2009 from a team led by Michael Mumma at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. They …